One of characteristics required for communication devices such as mobile communication terminals is low power consumption. In order to achieve the low power consumption, it is preferable to cause the communication device to be in a sleep mode. Patent Document 1 discloses that if a sleep request from a terminal to a base station is rejected, the sleep request is re-transmitted, and if the sleep request is rejected again, the sleep request is not transmitted until non-request response is received from the base station.